diff options
author | Nick Piggin <npiggin@suse.de> | 2006-03-23 14:01:02 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-23 18:38:17 +0300 |
commit | 0b2fcfdb8b4e7e379192f24ea2203163ddf5df1d (patch) | |
tree | 1f3995e41ab12ff76e737389e0b59a40c0c73668 /include | |
parent | 713729e8b993cb880225e2ced50a3f5ac05c2b3f (diff) | |
download | linux-0b2fcfdb8b4e7e379192f24ea2203163ddf5df1d.tar.xz |
[PATCH] atomic: add_unless cmpxchg optimise
Without branch hints, the very unlikely chance of the loop repeating due to
cmpxchg failure is unrolled with gcc-4 that I have tested.
Improve this for architectures with a native cas/cmpxchg. llsc archs
should try to implement this natively.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Andi Kleen <ak@muc.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/asm-i386/atomic.h | 8 | ||||
-rw-r--r-- | include/asm-ia64/atomic.h | 8 | ||||
-rw-r--r-- | include/asm-m68k/atomic.h | 8 | ||||
-rw-r--r-- | include/asm-s390/atomic.h | 18 | ||||
-rw-r--r-- | include/asm-sparc64/atomic.h | 10 | ||||
-rw-r--r-- | include/asm-x86_64/atomic.h | 8 |
6 files changed, 50 insertions, 10 deletions
diff --git a/include/asm-i386/atomic.h b/include/asm-i386/atomic.h index 78b0032d1f29..22d80ece95cb 100644 --- a/include/asm-i386/atomic.h +++ b/include/asm-i386/atomic.h @@ -225,8 +225,14 @@ static __inline__ int atomic_sub_return(int i, atomic_t *v) ({ \ int c, old; \ c = atomic_read(v); \ - while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + for (;;) { \ + if (unlikely(c == (u))) \ + break; \ + old = atomic_cmpxchg((v), c, c + (a)); \ + if (likely(old == c)) \ + break; \ c = old; \ + } \ c != (u); \ }) #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) diff --git a/include/asm-ia64/atomic.h b/include/asm-ia64/atomic.h index d3e0dfa99e1f..569ec7574baf 100644 --- a/include/asm-ia64/atomic.h +++ b/include/asm-ia64/atomic.h @@ -95,8 +95,14 @@ ia64_atomic64_sub (__s64 i, atomic64_t *v) ({ \ int c, old; \ c = atomic_read(v); \ - while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + for (;;) { \ + if (unlikely(c == (u))) \ + break; \ + old = atomic_cmpxchg((v), c, c + (a)); \ + if (likely(old == c)) \ + break; \ c = old; \ + } \ c != (u); \ }) #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) diff --git a/include/asm-m68k/atomic.h b/include/asm-m68k/atomic.h index 862e497c2645..732d696d31a6 100644 --- a/include/asm-m68k/atomic.h +++ b/include/asm-m68k/atomic.h @@ -175,8 +175,14 @@ static inline void atomic_set_mask(unsigned long mask, unsigned long *v) ({ \ int c, old; \ c = atomic_read(v); \ - while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + for (;;) { \ + if (unlikely(c == (u))) \ + break; \ + old = atomic_cmpxchg((v), c, c + (a)); \ + if (likely(old == c)) \ + break; \ c = old; \ + } \ c != (u); \ }) #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) diff --git a/include/asm-s390/atomic.h b/include/asm-s390/atomic.h index be6fefe223d6..de1d9926aa60 100644 --- a/include/asm-s390/atomic.h +++ b/include/asm-s390/atomic.h @@ -89,10 +89,15 @@ static __inline__ int atomic_cmpxchg(atomic_t *v, int old, int new) static __inline__ int atomic_add_unless(atomic_t *v, int a, int u) { int c, old; - c = atomic_read(v); - while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) + for (;;) { + if (unlikely(c == u)) + break; + old = atomic_cmpxchg(v, c, c + a); + if (likely(old == c)) + break; c = old; + } return c != u; } @@ -167,10 +172,15 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long long a, long long u) { long long c, old; - c = atomic64_read(v); - while (c != u && (old = atomic64_cmpxchg(v, c, c + a)) != c) + for (;;) { + if (unlikely(c == u)) + break; + old = atomic64_cmpxchg(v, c, c + a); + if (likely(old == c)) + break; c = old; + } return c != u; } diff --git a/include/asm-sparc64/atomic.h b/include/asm-sparc64/atomic.h index 25256bdc8aae..468eb48d8142 100644 --- a/include/asm-sparc64/atomic.h +++ b/include/asm-sparc64/atomic.h @@ -78,9 +78,15 @@ extern int atomic64_sub_ret(int, atomic64_t *); ({ \ int c, old; \ c = atomic_read(v); \ - while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + for (;;) { \ + if (unlikely(c == (u))) \ + break; \ + old = atomic_cmpxchg((v), c, c + (a)); \ + if (likely(old == c)) \ + break; \ c = old; \ - c != (u); \ + } \ + likely(c != (u)); \ }) #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) diff --git a/include/asm-x86_64/atomic.h b/include/asm-x86_64/atomic.h index 4b5cd553e772..cecbf7baa6aa 100644 --- a/include/asm-x86_64/atomic.h +++ b/include/asm-x86_64/atomic.h @@ -405,8 +405,14 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t *v) ({ \ int c, old; \ c = atomic_read(v); \ - while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + for (;;) { \ + if (unlikely(c == (u))) \ + break; \ + old = atomic_cmpxchg((v), c, c + (a)); \ + if (likely(old == c)) \ + break; \ c = old; \ + } \ c != (u); \ }) #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) |